1. Field of the Invention
The present invention relates to packer cups and more specifically to a thermally energized packer cup particularly suitable for sealing a pipe in a geothermal production well, an oil well, or a gas well.
2. Description of the Prior Art
Integral packer cups are commercially available devices used in oil, gas, and geothermal production wells to seal high and low pressure zones within the confines of the well. These cups are typically fabricated from elastomeric materials with metal reinforcing materials embedded in the elastomer. The cup is mounted on a mandrel or pipe prior to installation in the well. To effect a downwell seal, these cups are slightly oversized compared to the inner diameter of the well casing so as to bear against the casing wall. The seal is further enhanced by the resultant force due to the differential pressure across the seal. The integral packer cup as it is presently designed and fabricated has two major shortcomings. First, a portion of the elastomer material is necessarily removed during installation due to "rubbing" against the rough wall of the well casing thereby reducing or eliminating the interference fit between the cup and casing. This puts a higher dependency for effecting the seal on the resultant force due to the differential pressure. Also, the "rubbing" may expose the metal reinforcement embedded in the elastomer to corrosive fluids which may be present in the fluid to be sealed, resulting in premature seal failure. Secondly, the magnitude of the sealing force developed due to the interference is difficult to predict and control. Accordingly, there is a need for a packer cup which overcomes the shortcomings of the prior art.